Key Technical Points for Managing Young Citrus Trees for High Yield and Tree Shape

The management goal for young citrus trees is to promote multiple flushes of new shoots and the emergence of vigorous branches, accelerate the number of branching orders, form a full canopy as quickly as possible, and establish a strong framework, laying a good foundation for high and stable yields. To achieve this, the management technical measures should include:

1. Timely and appropriate fertilization

Young citrus trees are in the vegetative growth stage, with large root and new shoot growth and late cessation of growth. Fertilization should focus on meeting the nutrient needs of tree growth and new shoot emergence. The number of fertilizer applications and the amount applied should be determined by the growth vigor and growth characteristics of the young trees. Fertilization of young trees should follow the principles of frequent application, light application, and targeted application. Young trees can produce 3-4 flushes of shoots per year, with large growth, and in addition to fertilizer leaching and loss in the soil, they should be fertilized 7-9 times per year. The focus should be on applying quick-acting fertilizer before and during the growth periods of spring shoots, summer shoots, and autumn shoots. Nitrogen fertilizer should be the main type, combined with phosphorus and potassium fertilizers. The nitrogen, phosphorus, and potassium ratio is 5:1:3. Apply less or not at all to vigorous trees. Appropriately increase the number of fertilizer applications and the amount applied to weak trees. In late autumn or early winter, apply mainly organic fertilizer, appropriately combined with phosphorus and potassium fertilizers. Apply 20-50 kg of organic fertilizer, 0.5-1 kg of compound fertilizer, and 1-2 kg of calcium magnesium phosphate or ordinary calcium superphosphate per tree. This can improve soil physical and chemical properties and enhance soil enzyme activity. As the canopy expands rapidly, the amount of fertilizer applied should be gradually increased.

2. Cultivate a full canopy framework

Reasonable shaping and pruning can cultivate a tree shape with a strong canopy framework, uniform branching, a full canopy, and three-dimensional fruiting. The shaping of young trees should be determined according to planting density, cultivation technology level, terrain, variety, and other factors. Citrus tree shapes generally include round-headed, pagoda-shaped, natural open-center, hedge, and Y-shaped, among others. In view of factors such as the cultivated varieties and management level in the Jianshui area, young citrus trees are generally shaped as round-headed, pagoda-shaped, or natural open-center. In the shaping and pruning of young trees, in addition to reasonable trunk height determination and cultivation of a strong canopy framework, the most important thing is to pinch the new shoots, especially the extended summer shoots, to promote branching, increase the number of branching orders, rapidly form a full canopy, and achieve the goal of early high yield. When summer shoots and autumn shoots reach 20-30 cm in growth and the terminal bud has not yet lignified, pinch off the top 2-3 buds of the extended shoots on the outer part of the canopy, which plays a faster role in expanding the canopy. Branches inside the canopy that are too dense or overlapping should be removed or cut off early to reduce nutrient consumption.

3. Water management

In areas with prominent winter and spring drought, irrigate once before spring buds sprout to meet the water needs for new shoot sprouting and growth. Second, irrigate in combination with fertilization or apply fertilizer with water. Citrus orchards are most afraid of waterlogging. During the rainy season, drainage should be carried out promptly to lower the groundwater level below the root distribution layer, so as to avoid root rot and yellow leaves in citrus trees, which affect growth. Water management should generally follow the principles of spring irrigation, summer drainage, autumn control, and appropriate amounts in winter.

4. Pest and disease control

Common pests and diseases in the citrus production areas of Jianshui County include: citrus leafminer, red spider mite, citrus aphid, swallowtail butterfly, arrowhead scale, brown soft scale, anthracnose, scab, and powdery mildew, among others. In addition to strengthening cultivation management and enhancing tree resistance, winter orchard cleaning should be carried out, spraying lime sulfur mixture or sulfur suspension concentrate 2-3 times, once every 7-10 days, to eliminate overwintering pest and disease sources and reduce the damage index. During the growing season, according to the occurrence and development patterns of various pests and diseases in the field, at the peak hatching period of pest larvae and before disease occurrence, timely select high-efficiency, low-toxicity, and low-cost chemical pesticides or biological pesticides for spraying control. Attention should be paid to alternating and rotating pesticide types to reduce resistance and cost, improve control effectiveness, and keep pests and diseases below the allowable economic damage level.

5. Soil management

Young citrus trees are in a period of relatively large growth, and the soil should be kept loose and fertile, with no weeds growing densely. Intercropped plants should be 50-100 cm away from around the citrus trees. This gives young citrus trees a better living environment.

6. Foliar fertilization

In combination with pest and disease control, apply Guoshu Dongli 1000-fold solution, Gaomeishi 800-fold solution, and 0.3% zinc sulfate alternately by spraying on the leaf canopy. This can promptly meet the tree's nutrient absorption, enhance the physiological metabolic capacity of leaves, increase leaf photosynthetic intensity, and achieve the effect of strong branches and green leaves.

Through the careful management of the above comprehensive technical measures, even if the planted seedlings are one-year-old seedlings, they can enter the fruiting period in the third year. The average yield per mu can reach 1-1.5 tons, the yield doubles in the fourth year, and the yield per mu reaches 3-5 tons in the fifth year.